(1) Field of the Invention
The present invention relates to waterless urinals and, more particularly, to a waterless urinal cartridge that includes a mechanism for indicating a level of precipitate buildup within the cartridge to enable a user to know when to change the cartridge.
(2) Description of Related Art
Water is a scarce and diminishing resource in many areas of the world. It is widely recognized that more has to be done to conserve its usage as populations grow and climates change. Water conserving products are becoming more and more important not only for quality of human life but also for sanitary and subsistence reasons.
There have been many water conserving measures taken all over the world in an effort to deal with limited and diminishing resources. Many municipalities have developed rationing plans while others have invested in waste water recycling treatment and re-use. There have also been many water-conserving products introduced into the marketplace. These products are being more widely used by industry and homeowners as regulations become stricter and the costs of water usage rise.
The non-flushing urinal designs use far less water than the traditional urinals, saving up to 40,000 gallons of water per year from a single urinal. The non-flushing urinals are made of three major components: a porcelain urinal, a housing, and a cartridge. The porcelain urinal component is very similar to a traditional urinal. The housing replaces a traditional P-trap which normally would connect a urinal to the building's plumbing. Thus, the housing sits in-line between the building's plumbing and the bottom of the urinal where the drain pipe would normally connect. The cartridge operates as the P-trap and fits in the housing in a sealed air-tight manner and can be removed for servicing and replacement.
The liquid trap-style cartridge serves two purposes. First, it acts as a barrier from sewer gasses and odors coming into the restroom. Second, it acts as a filter; removing some of the solids that precipitate from human urine (which is a super saturated liquid). Human urine is an aqueous solution of greater than 95% water, with the remaining constituents, in order of decreasing concentration being urea 9.3 g/L, chloride 1.87 g/L, sodium 1.17 g/L, potassium 0.750 g/L, creatinine 0.670 g/L, and other dissolved ions, inorganic and organic compounds according to the NASA Contractor Report No. NASA CR-1802, D. F. Putnam, July 1971.
The liquid trap-style cartridge works by using two mechanisms. First, urine fills the P-trap of the cartridge, forming a barrier against sewer gasses—just as the water does in a traditional P-trapped urinal. Second, a layer of low density fluid, such as oil, can be poured into the trap so that it floats on top of the urine. This floating fluid forms a barrier keeping unpleasant urine smells from entering the bathroom. As a user urinates into the urinal, fresh urine enters the cartridge, sinks through the floating fluid barrier, and presses the old urine out of the trap and out through the housing exit tube and into the building's plumbing.
Though there are significant water saving benefits from using the non-flushing urinals, some drawbacks exist. One of the most significant is the formation of struvite in the pipes, the housing, and the cartridge. Struvite (magnesium ammonium phosphate) is a phosphate mineral with formula: NH4MgPO4.6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platy mica-like forms. It is a soft mineral with a Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7. It is sparingly soluble in neutral and alkaline conditions, but readily soluble in acidic conditions. In some cases, formation of struvite in the cartridge can be beneficial, as struvite formed in the cartridge is struvite not deposited in the housing or pipes. The cartridge is designed to be easily replaceable, thus its action as a filter is a benefit.
Because the flow of the new fluids (both flushing and/or urine) is affected by the location of the buildup, it is important to note how struvite or other solids build up inside the cartridge. The waterless urinal cartridges are designed to filter solids out of urine and, consequently accumulate buildup over time. This buildup tends to rest mainly on the surfaces where turbulence occurs inside the cartridge and where gravity deposits the heavier-than-urine solids. Thus the cartridge can act as a filter, taking out some solids to avoid them building up in the building's plumbing.
Codes and regulations in many countries also affect cartridge design. In the United States, for example, the plumbing code typically requires a two inch vertical liquid barrier to sewer gasses. Thus, unless another component provides the trap action, the cartridge must be designed to hold a two inch column of water in order to comply with the United States Plumbing Code. Because the trap area is the area most likely to have struvite sediment clog it, it is advantageous for the cartridge (which is easily replaceable) to be the component that provides this two inch gas sealing water column as required by the United States Plumbing Code.
There are a number of different designs of liquid trap cartridges. All United States Plumbing Code compliant models utilize a 2″ deep water column to block sewer gas while some utilize a central exit and some utilize a side exit. United States Plumbing Code compliant cartridges similar to those made by Falcon Waterfree Technologies (located at 2255 Barry Avenue, Los Angeles, Calif. 90064, USA) use a central inlet for the fluid to enter and a side or back exit for the fluid to exit the cartridge. Others, similar to the cartridge manufactured and sold under the Waterless brand (Waterless Co., 1050 Joshua Way, Vista, Calif. 92081, USA) utilize inlets spaced away from the center and closer to the perimeter of the cartridge, and a central cartridge exit.
All of these designs have one thing in common—over time, they fill-up with solid sediment from urine and eventually become clogged-up. Once clogged-up, the cartridges need to be replaced. This works well, but has one specific disadvantage: there is no adequate warning system for when the cartridge is full. When the cartridge is full, the urinal often becomes clogged and is left with a pool of urine in the bowl as an indicator that the time has come to replace the cartridge. The replacement of the cartridge in this circumstance can be onerous, as the service person has to deal with the pool of urine in the bowl in order to access the cartridge below. Thus, there is a need for a waterless urinal cartridge lifecycle expiration warning system to assist maintenance personnel in changing cartridges before they become clogged and urine begins to pool. Such warning system would indicate the pending need for a change, prior to the cartridge becoming completely clogged-up.